Ocean Sunfish-At 1,000 kilograms (the weight of an average car) this is the heaviest known bony fish in the world. The heaviest known specimen weighed nearly 5,000 pounds and was 14 feet long. They are not dangerous to humans and in fact are known to interact with them. They do however, jump into boats, causing damage to them. They are found virtually in every ocean, particularly large numbers in the Atlantic and Pacific.